What is the code signing trust level?

Question

Created Jul ’25

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In some crashlog files, there are additional pieces of information related to codesigning.

I can understand what most of themcorresponds to (ID, TeamID, Flags, Validation Category). But there is one I have some doubt about: Trust Level.

As far as I can tell (or at least what Google and other search engines say), this is an unsigned 32 bit integer that defines the trust level with -1 being untrusted, 0, being basically an Apple executable and other potential bigger values corresponding to App Store binaries, Developer ID signature, etc.

Yet, I'm not able to find a corresponding detailed documentation about this on Apple's developer website.

I also had a look at the LightweightCodeRequirements "include" file and there does not seem to be such a field available.

[Q] Is there any official documentation listing the different values for this trust level value and providing a clear description of what it corresponds to?

Answered by DTS Engineer in 849908022

Is there any official documentation listing the different values for this trust level value and providing a clear description of what it corresponds to?

No. The canonical documentation for the JSON side of a crash report is Interpreting the JSON format of a crash report, and codeSigningTrustLevel is not listed there. I encourage you to file a bug against that doc.

Please post your bug number, just for the record.

If you want to dig into the implementation details, much of that is the Darwin open source. A good thread to pull on is TASK_CRASHINFO_CS_TRUST_LEVEL in the xnu project. However, that’s not the same as documentation, and hence my answer above.

I will note, however, that 4294967295 is 0xffffffff, which is the value of KCDATA_INVALID_CS_TRUST_LEVEL.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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Answer 1

DTS Engineer OP

Apple

Jul ’25

I want to make sure we’re talking about the same thing here. Please post an example crash report and point out the line number of concern. See Posting a Crash Report for advice on how to post a crash report.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

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Answer 2

packagesdev OP

Jul ’25

  "codeSigningID" : "testException-55554944e0bd51c1d54834c8a36f3f6a2e7a6e6b",
  "codeSigningTeamID" : "",
  "codeSigningFlags" : 570425861,
  "codeSigningValidationCategory" : 10,
  "codeSigningTrustLevel" : 4294967295, <--- here
  "codeSigningAuxiliaryInfo" : 0,

testException-2025-06-02-234012 copy.txt

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Answer 3

DTS Engineer OP

Apple

Jul ’25

Recommended

Is there any official documentation listing the different values for this trust level value and providing a clear description of what it corresponds to?

No. The canonical documentation for the JSON side of a crash report is Interpreting the JSON format of a crash report, and codeSigningTrustLevel is not listed there. I encourage you to file a bug against that doc.

Please post your bug number, just for the record.

If you want to dig into the implementation details, much of that is the Darwin open source. A good thread to pull on is TASK_CRASHINFO_CS_TRUST_LEVEL in the xnu project. However, that’s not the same as documentation, and hence my answer above.

I will note, however, that 4294967295 is 0xffffffff, which is the value of KCDATA_INVALID_CS_TRUST_LEVEL.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0

Answer 4

packagesdev OP

Jul ’25

Thanks. Those are interesting pointers to explore.

0